INTRODUCTION
Tree nut (TN) and peanut allergy prevalence has been increasing over the last 20 years, particularly in pediatric age, as a presumable result of changes in recent eating habits.1-3
Allergy prevalence for each TN appears to vary in different parts of the world. A current systematic worldwide review of studies estimated the global prevalence of probable TN allergy to range from 0.05% to 4.9%, and peanut allergy between 0.5% and 2.5%.1,4,5
These food allergies can be potentially life-threatening, accounting for a high number of fatal food-induced anaphylaxis, even when ingested in very small quantities or inadvertently, as occult allergens.1-3 Recent studies reported TN and peanut allergies as the responsible for 70–90% of deaths from food-induced anaphylaxis, with TN alone accounting for 18–40%.6
TN and peanut allergies usually develop early in life and tend to persist into adulthood. According to previous published data, acquisition of natural tolerance to TN and peanut occurs in only 9%–20% of allergic patients.7-9
The constant need for caution when choosing food and the potential risk of anaphylaxis, frequently leading to diet and social activities restrictions, significantly affects both patient and family’s quality of life. Presently, and regardless of years of research, the management cornerstone of these patients remains strict avoidance of the incriminated nut, in addition to patient and family’s education on prompt recognition of anaphylaxis and immediate use of adrenaline.10,11 Other treatment possibilities have been largely explored, namely oral immunotherapy, for peanut and TN allergic patients, but their use is still limited.12
Homology amongst nut proteins and cross-reactivity between their main allergens (namely 2S albumins, 7S and 11S globulins, lipid transport proteins [LTPs], and PR-10) leads to frequent co-sensitization in nut allergic patients, which does not always mean a true concurrent allergy to different nuts.13 As a result, it can be challenging to manage these patients and a distinction between cross-sensitization and clinically relevant cross-reactivity between different TN and peanut is critical, although it frequently requires multiple oral food challenges (OFC) with the associated risk of a possible anaphylaxis. For this fact, dietary restriction of all TN and peanut is a common practice. Deeper knowledge of sensitization patterns and investigation of possible anaphylaxis predictors would be of great value to establish a more precise diagnostic approach and individual dietary guidance for patients allergic to these foods.1-5
In non-English-speaking countries, like Portugal, data on sensitization patterns and anaphylaxis predictors is sparse. We aimed to characterize a pediatric cohort with TN and peanut allergy followed in an Immunoallergology department of a Portuguese tertiary hospital, and to assess the utility of skin tests (ST), specific IgE (sIgE) and molecular components (mcIgE), as well as ratio sIgE/total IgE in predicting the anaphylaxis risk.